Membrane switch

• US 5,401,922 A
• Filed: 04/25/1994
• Issued: 03/28/1995
• Est. Priority Date: 02/22/1993
• Status: Expired due to Term

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Asta, Joseph L.
• Primary Examiner(s): Pellinen, A. D.
• Assistant Examiner(s): Friedhofer, Michael A.
• Application Number:
  US08/231,868
• Time in Patent Office: 337 Days
• Field of Search: 200/5 R, 200/5 A, 200/61.54, 200/61.55, 200/85, 200/86 R, 200/511, 200/512, 200/306, 280/728, 280/731
• US Class Current: 200/5.00A
• CPC Class Codes: B60Q 5/003 mounted on the steering wheel
• CPC Class Codes: B60R 21/203 in steering wheels or steering columns
• CPC Class Codes: H01H 3/141 Cushion or mat switches

Abstract

A membrane switch including first and second substantially flexible electrical contacts and a first layer of dielectric material deposited between and on one surface of one of the first and second contacts, the first layer being deposited in a predetermined geometric pattern including a plurality of cells defined by cell walls, the cell walls being broken in predetermined positions about the perimeter of each cell so that during and after actuation of the switch, air within a cell between the first and second contacts can vent to one or more adjoining cells to enable activation and prevent a vacuum from forming between the first and second contacts thereby enabling the switch to break contact after being released.

Claims

1. A membrane switch, comprising:

first substantially flexible electrical contact means;

second substantially flexible electrical contact means;

a first layer of dielectric material disposed upon one surface of said first electrical contact means so as to be interposed between said first and second electrical contact means, said first layer of dielectric material comprising a plurality of contiguous cells arranged in a predetermined geometrical pattern; and

a second layer of dielectric material disposed upon one surface of said second electrical contact means so as to be interposed between said first and second electrical contact means and in contact with said first layer of dielectric material disposed upon said one surface of said first electrical contact means, said second layer of dielectric material comprising a plurality of contiguous cells arranged in a predetermined geometrical pattern which is substantially identical to said geometrical pattern of said cells of said first layer of dielectric material such that said first and second electrical contact means, having said first and second layers of dielectric material disposed thereon, are effectively interchangeable,

wherein each one of said cells of said first and second layers of dielectric material has the configuration of a polygon which is defined by means of a predetermined number of vertices, and a predetermined number of sides defining cell walls of said cells which are shared by adjoining cells, said cell walls of said first and second layers of dielectric material being broken in predetermined positions about the perimeter of each cell and being in alignment with respect to each other so that, during and after actuation of said switch, air within any one cell disposed within an actuated area of said switch and between said first and second electrical contact means can vent to one or more adjoining cells, and can receive air back from said one or more adjoining cells, so as to enable activation of said switch and prevent a vacuum from forming between said first and second electrical contact means thereby enabling said switch to break contact after being depressed and released.

2. The membrane switch as defined in claim 1 wherein said geometric pattern includes a series of hexagons defining a plurality of cells where each of the six sides of the hexagons are broken proximate a midpoint thereof.

3. The membrane switch as defined in claim 1 wherein said first and second contact means are provided by depositing a conductive layer of material on a respective first and second flexible substrate.

4. The membrane switch as defined in claim 1 wherein said first and second electrical contact means are secured about their perimeters with an adhesive to environmentally protect the switch contacts by preventing infiltration of the elements therebetween.

5. The membrane switch as defined in claim 1 wherein a resilient member is provided on an exterior surface of at least one of said first and second contact means to distribute both mechanical and electrical switch loads over more than one cell.

6. A membrane switch as set forth in claim 1, wherein:

said cells have a predetermined size which determines the amount of force necessary to actuate said switch.

9. The assembly as defined in claim 5 wherein said first and second electrical contact means are secured about their perimeters with an adhesive to environmentally protect the switch contacts by preventing infiltration of the elements therebetween.

7. An air bag assembly, comprising:

housing means having at least one opening defined therethrough;

air bag means mounted within said housing means;

an outer cover member enclosing said at least one opening defined within said housing means and securing said air bag means therein, said outer cover member being capable of enabling release of said air bag means through said at least one opening defined within said housing means and through said outer cover member when said air bag means is activated; and

membrane switch means mounted between said air bag means and said outer cover member and which can be activated by a user through said outer cover member, and enable unimpeded deployment of said air bag means while preventing damage to said air bag means and injury to said user;

said membrane switch means including first and second substantially flexible electrical contact means;

a first layer of dielectric material disposed upon one surface of said first electrical contact means so as to be interposed between said first and second electrical contact means, said first layer of dielectric material comprising a plurality of contiguous cells arranged in a predetermined geometrical pattern; and

a second layer of dielectric material disposed upon one surface of said second electrical contact means so as to be interposed between said first and second electrical contact means and in contact with said first layer of dielectric material disposed upon said one surface of said first electrical contact means, said second layer of dielectric material comprising a plurality of contiguous cells arranged in a predetermined geometrical pattern which is substantially identical to said geometrical pattern of said cells of said first layer of dielectric material such that said first and second electrical contact means, having said first and second layers of dielectric material disposed thereon, are effectively interchangeable;

wherein each one of said cells of said first and second layers of dielectric material has the configuration of a polygon which is defined by means of a predetermined number of vertices, and a predetermined number of sides defining cell walls of said cells which are shared by adjoining cells, said cell walls of said first and second layers of dielectric material being broken in predetermined positions about the perimeter of each cell and being in alignment with respect to each other so that, during and after actuation of said switch, air within any one cell disposed within an actuated area of said switch and between said first and second electrical contact means can vent to one or more adjoining cells, and can receive air back from said one or more adjoining cells, so as to enable activation of said switch and prevent a vacuum from forming between said first and second electrical contact means thereby enabling said switch to break contact after being depressed and released.

8. The assembly as defined in claim 7 wherein said geometric pattern includes a series of hexagons defining a plurality of cells where each of the six sides of the hexagons are broken proximate a midpoint thereof.

10. The assembly as defined in claim 7 wherein said outer cover member is a resilient member which assists in distributing both mechanical and electrical switch loads over more than one cell.

11. An assembly as set forth in claim 7, wherein:

said cells have a predetermined size which determines the amount of force necessary to actuate said membrane switch means.

12. An assembly as set forth in claim 7, wherein:

said housing means comprises a steering wheel housing of a motor vehicle.

13. An assembly as set forth in claim 12, wherein:

said membrane switch means comprises a horn switch of said motor vehicle.